fixes #25094, type params in static methods shouldn't always be an error

pkg/analyzer/lib/src/generated/error_verifier.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library engine.resolver.error_verifier;
 
 import 'dart:collection';
 import "dart:math" as math;
 
 import 'package:analyzer/src/generated/static_type_analyzer.dart';
@@ skipping 5220 matching lines @@
   /**
    * Check whether the given type [name] is a type parameter being used to
    * define a static member.
    *
    * See [StaticWarningCode.TYPE_PARAMETER_REFERENCED_BY_STATIC].
    */
   bool _checkForTypeParameterReferencedByStatic(TypeName name) {
     if (_isInStaticMethod || _isInStaticVariableDeclaration) {
       DartType type = name.type;
       if (type is TypeParameterType) {
-        _errorReporter.reportErrorForNode(
-            StaticWarningCode.TYPE_PARAMETER_REFERENCED_BY_STATIC, name);
-        return true;
+        // The class's type parameters are not in scope for static methods.
+        // However all other type parameters are legal (e.g. the static method's
+        // type parameters, or a local function's type parameters).
+        if (type.element.enclosingElement is ClassElement) {
+          _errorReporter.reportErrorForNode(
+              StaticWarningCode.TYPE_PARAMETER_REFERENCED_BY_STATIC, name);
+          return true;
+        }
       }
     }
     return false;
   }
 
   /**
    * Check whether the given type [parameter] is a supertype of its bound.
    *
    * See [StaticTypeWarningCode.TYPE_PARAMETER_SUPERTYPE_OF_ITS_BOUND].
    */
@@ skipping 851 matching lines @@
     toCheck.add(type.element);
     // type arguments
     if (type is InterfaceType) {
       InterfaceType interfaceType = type;
       for (DartType typeArgument in interfaceType.typeArguments) {
         _addTypeToCheck(typeArgument);
       }
     }
   }
 }